Differences in circadian rhythm changes between myopic and non-myopic college students over 2 years

This study aimed to characterize and compare the differences in circadian rhythm changes during 2 years between college students with myopia and non-myopia based on a longitudinal cohort study. Wake-up time and bedtime were obtained through a self-administered questionnaire. Chronotype was assessed using the reduced Morningness-Eveningness Questionnaire (rMEQ). Circadian rhythm timing was determined by dim-light melatonin onset (DLMO), measured through hourly saliva collection from 21:00 to 01:00. A total of 450 college students (146 [32.4%] males) with a mean age of 18.65 ± 1.05 years were included, of whom 353 (78.4%) students had myopia. Compared with non-myopic individuals, myopic students slept later, woke up earlier, and exhibited lower rMEQ scores at baseline. Over the 2-year follow-up, both groups showed significantly earlier bedtimes, later wake-up times, and higher rMEQ scores. Only myopic students demonstrated a 45-minute delay in DLMO after the 2-year follow-up. After adjusting for potential confounders, linear mixed-effects models showed that myopic individuals had later bedtimes and earlier wake-up times. These findings indicate significant circadian rhythm changes in individuals with myopia, suggesting the potential of targeted sleep rhythm interventions on preventing myopia.